Most buildings are constructed of a combination of columns (i.e., posts) and beams, which are covered by plywood or some sort of metal or plastic sheeting. In an effort to reduce the overall construction time, however, contractors often construct buildings, and particularly, the exterior walls of buildings, with prefabricated building panels. Constructing a building with such panels increases productivity because entire walls are manufactured directly at the construction site so that they can be swiftly combined and erected.
These prefabricated panels are typically manufactured from steel sheet metal, and configured to conform to the desired shape of the building. For example, an arch style building 100, such as the one illustrated in FIG. 1, is comprised of a plurality of interconnected arch shaped panels. The panels are interconnected by placing them adjacent one another and forming a sealed joint where the edges of the panels overlap. Thus, the length of the building is not only dependent upon the width of each panel, but it is also a function of the overall number of interconnected panels.
In addition to constructing arch shaped buildings, panels may be used to construct gable style buildings 200 and double radius style buildings 300, such as those illustrated in FIGS. 2 and 3, respectively. Although not shown, interconnected panels can also be used to construct straight sided buildings or portions thereof. Regardless of whether the building has a curved or straight profile, the cross section of the panels used to construct such buildings are sometimes similar.
For example, FIG. 4 illustrates a cross section of a known building panel typically used to construct such buildings. The building panel 400 includes a central portion 402 and two inclined side wall portions 410, 412 extending from opposite ends of the central portion 402. The central portion 402 is straight, and in order to increase that portion's stiffness it may include a notched portion 408. Assuming the central portion includes a notched stiffener, the central portion 402 would be separated into two sub-central portions 404, 406. Although such a feature is not shown, the inclined side wall portions 410, 412 may also include notches to stiffen those portions of the building panel.
Continuing to refer to FIG. 4, the building panel 400 further includes two wing portions 414, 416 extending from the inclined side wall portions 410, 412, respectively. The wing portions 414, 416 are substantially parallel to the straight central portion 402 and may include notch stiffeners 422, 424. A hem portion 420 extends from one wing portion 416, and a complementary hook portion 418 extends from the other wing portion 414.
Referring to FIG. 5, there is shown a building structure 500 comprising two building panels 400 interconnected by the complementary hem 420 and hook portions 418. Referring to FIG. 5A, which is an enlarged view of the connection, the hem portion 420 comprises an inclined hem section 430 and an end section 432. The hook portion 418 comprises a complementary inclined section 434, an intermediate section 436 parallel to the wing portions, and an end section 438. As discussed in U.S. Pat. No. 5,393,173, which is hereby incorporated by reference, the end section 432 of the hem portion 420 snaps into place adjacent the intermediate section 436 of the hook portion 418. After the hem portion 420 snaps in place, a seaming device bends the end section 438 of the hook portion 418 up and in toward the end section 432 of the hem portion 420. Bending the end section 438, therefore, seams the two panels 400 together to form a single building structure 500.
As mentioned above, the length of the building increases with the number of interconnected panels. The length of the building is also dependent upon the width of each panel. The width of the building, on the other hand, is a function of the length of each panel. Thus, the overall size of the building is dependent upon the dimensions of each panel and the total number thereof.
As the size of each panel increases, so does its weight. Because weight is a gravitational force, which imparts a moment upon structures, as the width and length of each panel increases, the panel is subject to greater moments. Although it has been exaggerated for the purposes of explanation herein, FIG. 6 illustrates an arch shaped panel 600 subject to both positive and negative bending moments resulting from the weight of the panel. Particularly, the weight of building panel 100 illustrated in FIG. 1, imparts negative bending moments at locations 602 and 604 and positive bending moments at the location identified as 606. Although the central portion of the panel includes a notch stiffener, the typical design of such panels often results in subjecting the panel to a greater negative bending moment, thereby increasing the tendency of distorting the panel's original configuration, as exaggerated in FIG. 6.
Similarly, the gable style building 200 and double radius style building 300, illustrated in FIGS. 2 and 3, respectively, are also subject to undesirable bending moments. As illustrated in FIG. 7, the gable style building 200 is subject to negative bending moments in the regions identified as 702 and 704, which overcome the positive bending moment of region 706, thereby creating an overly emphasized distorted building panel 700. Furthermore, as illustrated in FIG. 8, the double radius style building 300 is subject to negative bending moments in the regions identified as 802 and 804, which overcome the positive bending moment of region 806, thereby creating an overly embellished disfigured building panel 800.
As the size of the building structure increases, so does its weight. Therefore, as the size of the building structure increases, the building panels are subject to increased bending moments, the direction of which are dependent upon the orientation of the building structure. The inability of the building panels to withstand such bending moments, in turn, imparts design constraints on the building, thereby limiting its overall size and shape. Accordingly, there is a need to improve the panel's ability to withstand greater bending moments.